The disposal of waste both from municipal and industrial sources, such as trash, rubbish, garbage, animal wastes, agricultural wastes, and waste of plastic processing operations is rapidly becoming of immense national concern. The cost of disposal ranks third behind public schooling and highways as municipal expense in the United States.
It is estimated that each individual in the country generates between 4 and 6 pounds of waste per day, that the industrial output is equivalent to approximately 5 pounds of solid waste per person per day. Previous methods of mass waste disposal, such as landfill, are becoming impossible, while others such as incineration are costly and result in air pollution problems.
A vast majority of the waste which is presently disposed of contains products which are immediately recyclable back into the economy or products into which the waste can be converted for recycle back to the economy. Directly recyclable constituents are the various metals present, such as aluminum and steel, and glass. For the most part, the organic solid waste fraction is subjected to flash pyrolysis as an operation independent of recovery of the directly recyclable inorganic fraction and any organic portion recovered as pulp. Flash pyrolysis in the presence of an inorganic heat source or ash yields carbon containing solid residue or char, condensible pyrolytic oils and combustible gases. The solid particles are removed from the liquid and gas constituents mechanically by cyclone separators. The oil and gas are valuable by-products, part of the gas being recycled to provide energy to the system.
After separation, it is necessary to fluidize the solid particles by mixing them with recycled product gas and direct them into a combustion chamber where the particles are mixed with a source of oxygen, typically air and cause decarbonization of the carbon containing solid residue of pyrolysis to reheat the inorganic heat source and generate from the carbon containing solid residue of pyrolysis additional inorganic heat source. However, before the particles can be fluidized, they must be stripped of any residual oil which tends to make the particles stick together and also to recover the oil before combustion takes place.